1. Summary of the Invention
This invention relates to improved ported gate valves and, more particularly, to ported gate valves formed with a primary seal to atmosphere between their gate plate and sleeves and with a secondary seal to atmosphere between their gate plate and packing.
2. Description of the Background Art
In the field of fluid handling, it is a common practice to insert a valve along lengths of pipes so that the flow of fluids through the pipes may be selectively interrupted or continued at the control of an operator. One common type of valve is that formed with an apertured housing and an imperforate, reciprocable plate or gate having a knife edge. Such valves are commonly called knife gate valves or gate valves. The gate with the knife edge is slidably reciprocable into and out of the housing. The housing is coupled to adjacent ends of coupled pipes. When the gate is retracted out of the housing, the valve is open to allow the flow of fluid through the pipes and housing. When the gate is advanced into the housing, the apertures of the housing are blocked by the gate and the flow of fluid through the pipes and housing is precluded. The most common form of knife gate valves are unidirectional with metal seals which do not provide bubble tight shut off. In another form of knife gate valves, that of Clarkson in U.S. Pat. No. 4,257,447, the housing halves on opposite sides of the gate are secured on their axially exterior faces to the pipes while their interior faces are provided with elastomeric sleeves in tight compressive contact when the gate is retracted to ensure the flow of fluid therethrough without leakage. The advancement of the knife edge of the gate to terminate the flow of fluids causes even further compression of the sleeve. Movement of the gate is effected through an actuator thereabove.
In view of the large number of fixed and movable parts to use, operate, maintain and repair, a typical knife valve requires constant attention by a skilled operator. Additionally, the movement of the knife edge of the gate may cause damage to the contacted seal members of the housing upon movement of the gate to the closed position. Further, sealing sleeves in constant high and varying compression as found in knife valves have decreased lives.
A typical knife valve is disclosed in the patent to Clarkson referred to above. Such knife valve suffers from all of the shortcomings as enumerated above. Further, as is typical in many knife valves, the gate slides against metal guide rings which cause excessive wear of the gate as well as of the guide rings thereby necessitating expensive repairs and resulting in costly down time. Such metal to metal contact also accelerates corrosion. In addition, the sealing sleeves of Clarkson are of a multi-piece construction which increases cost, complexity, repair problems, and enlargement of the stock of repair parts.
Modified knife valves of the Clarkson type have also been used. While such modified knife valves have extended utility over those of the type described in the Clarkson patent, most of the above-enumerated shortcomings continued, particularly the sleeve being under heavy compression at all times, as well as the wearing on metal to metal surfaces.
The prior art knife gate valves often have wide faces with increased thickness to accommodate the complex mechanisms within the sleeve. As such, prior art valves may not be of an industry standard size for retrofit purposes. The present invention achieves high performance operations of knife valves while allowing retrofit to the industry standard sizes. The present invention also allows for sleeve replacement without valve disassembly and allows the replacement of the valve to different locations without disassembling the valve or making piping changes.
An optimum assembly would be something new which combines the benefits of the prior practices without their shortcomings, i.e., an assembly which provides for the efficient gating of pipes; convenient and simplified operation, repair, replacement, etc., reliable operation over an extended life of valves and their component elements; and economical cost to manufacture operate, maintain and repair.
As illustrated by a great number of prior commercial devices as well as patents, efforts are continuously being made in an attempt to improve valves whereby pipes may convey fluids more efficiently, conveniently, reliably and economically. None of these previous efforts, however, provides the benefits attendant with the present invention. Additionally, prior valves do not suggest the present inventive combination of component elements arranged and configured as disclosed and claimed herein. The present invention achieves its intended purposes, objectives and advantages over the prior art devices through a new, useful and unobvious combination of component elements, with the use of a minimum number of functioning parts, at a reduced cost to manufacture, and by employing only readily available materials.
Therefore, it is an object of this invention to provide an improved gate valve comprising spaced parallel housing walls having axially aligned apertures therethrough and constituting a housing; sleeves removably coupled to the housing walls and defining an annular space therebetween; a gate plate in sliding contact with the sleeves reciprocable between open and closed positions and defining a primary seal to atmosphere between the gate plate and sleeves; packing located adjacent to the upper edges of the housing walls through which the gate plate reciprocates between open and closed positions and defining a secondary seal to atmosphere between the gate plate and the packing; and means associated with the periphery of the housing walls to retain flowing fluid within the housing walls.
It is a further object of this invention to create seals in a ported gate valve with a gate plate in sliding contact with spaced sleeves reciprocable between open and closed positions to define a primary seal between the gate plate and sleeves and with packing located adjacent to the upper edges of housing walls through which the gate plate reciprocates between open and closed positions to define a secondary seal between the gate plate and packing.
It is a further object of this invention to extend the life of gate valves by retaining the elastomeric sealing sleeves out of contact with each other during operation and use.
It is a further object of the invention to eliminate pressure in the body extension and the other parts of the body when the gate plate is in the closed position.
It is a further object of the invention to introduce fluid to, or remove fluid from, the housing of a gate valve.
Lastly, it is an object of this invention to retain conveyed fluids within a gate valve by the use of a lower body extension beneath sealing sleeves spaced from each other.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.